Countdown to Pluto

Jan 15, 2014 by Dr. Tony Phillips

An artist's concept of the New Horizons spacecraft at Pluto. Image Credit: Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute. Credit: JHUAPL/SwRI

One of the fastest spacecraft ever built—NASA's New Horizons—is hurtling through the void at nearly one million miles per day. Launched in 2006, it has been in flight longer than some missions last, and it is nearing its destination: Pluto.

"The encounter begins next January," says Alan Stern, of the Southwest Research Institute and the mission's principal investigator. "We're less than a year away."

Closest approach is scheduled for July 2015 when New Horizons flies only 10,000 km from Pluto, but the spacecraft will be busy long before that date. The first step, in January 2015, is an intensive campaign of photography by the Long Range Reconnaissance Imager or "LORRI." This will help mission controllers pinpoint Pluto's location, which is uncertain by a few thousand kilometers.

"LORRI will photograph the planet against known background star fields," explains Stern. "We'll use the images to refine Pluto's distance from the spacecraft, and then fire the engines to make any necessary corrections."

At first, Pluto and its large moon Charon will be little more than distant pinpricks-"a couple of fat pixels," says Stern—but soon they will swell into full-fledged worlds.

By late April 2015, the approaching spacecraft will be taking pictures of Pluto that surpass the best images from Hubble. By closest approach in July 2015, a whole new world will open up to the spacecraft's cameras. If New Horizons flew over Earth at the same altitude, it could see individual buildings and their shapes.

Stern is looking forward to one of the most exciting moments of the Space Age.

"Humankind hasn't had an experience like this—an encounter with a new planet—in a long time," he says. "Everything we see on Pluto will be a revelation."

He likens New Horizons to Mariner 4, which flew past Mars in July 1965. At the time, many people on Earth, even some scientists, thought the Red Planet was a relatively gentle world, with water and vegetation friendly to life. Instead, Mariner 4 revealed a desiccated wasteland of haunting beauty. New Horizons' flyby of Pluto will occur almost exactly 50 years after Mariner 4's flyby of Mars-and it could shock observers just as much.

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Other than a few indistinct markings seen from afar by Hubble, Pluto's landscape is totally unexplored. Although some astronomers call Pluto a "dwarf" planet, Stern says there's nothing small about it. "If you drove a car around the equator of Pluto, the odometer would rack up almost 5,000 miles-as far as from Manhattan to Moscow." Such a traveler might encounter icy geysers, craters, clouds, mountain ranges, rilles and valleys, alongside alien landforms no one has ever imagined.

"There is a real possibility that New Horizons will discover new moons and rings as well," says Stern.

Yes, Pluto could have rings. Already, Pluto has five known moons: Charon, Styx, Nix, Kerberos, and Hydra. Numerical simulations show that meteoroids striking those satellites could send debris into orbit, forming a ring system that waxes and wanes over time in response to changes in bombardment.

"We're flying into the unknown," says Stern, "and there is no telling what we might find."

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Gee, at a million miles a day, it would still take 12,330 years to get to Alpha Centauri. Something tells me we're still too primitive at this science. We have to do things to improve it. For example, New Horizons is cruising. With an ion thruster engine, it could be accelerating at a constant rate, and the craft would not take this long to get to where it is going.

Do you even know what Trojans are and why they are where they are? If you did you would realize that it's impossible for a planet to clear any Trojans it has because it will never catch up with them.

It's impossible for Pluto to clear everything in it's orbit, because it too will never catch up with them; It "Crosses" Neptune's orbit, but it's not even on the same plane, at least it would take longer than the Sun's lifetime before a collision happened.

It's not about whether it will catch up or not. They made a rule, and then they made an exception to their own rule because they realized the other planets don't actually meet the requirements either.

There are other objects crossing over, or near, our orbits all the time, which everybody knows this.

Somehow Pluto and her moons don't seem as though they will offer anything special. Plus it takes for ever to get there. Other than raw materials none of our neighboring planets have any practical value in terms of sustaining life as we know it. Let's build a very large self sustaining ship in orbit like we did with the space station. Then load it with the willing and send them off to find the next viable planet. Spending huge money to visit space rocks seems rather trivial. Why isn't there at least an experimental station on the moon for long term studies of man and material under the extremes of little atmosphere and reduced gravity. We could have racked up years of valuable data. Instead we blow billions on wars. Maybe we need to be reduced to sticks and stones in order that we might start over with better results.

IMO, the dwarf planet Pluto should always be referred to as the planet Pluto, the same way that ex-Mayors, ex-Senators, ex-Governors, and ex-Presidents get to keep their honorary titles for life, as a matter of respect for having once held a position of such honor. In planetary science, I imagine it will never happen again.

@Mayday: It's a classification of a celestial body, not an honorary position or title. It's not a person, it doesn't have feelings, and it doesn't require respect. It's a rock. A special rock, yes, but still a rock.

Going by your thought process, it would be like someone saying a rock is gold even after finding out it's pyrite because they want to show it respect for once having the honor of being thought of as gold.

IMO, the dwarf planet Pluto should always be referred to as the planet Pluto, the same way that ex-Mayors, ex-Senators, ex-Governors, and ex-Presidents get to keep their honorary titles for life, as a matter of respect for having once held a position of such honor. In planetary science, I imagine it will never happen again.

IMO, the dwarf planet Pluto should always be referred to as the planet Pluto

It's a label. It doesn't mean anything. A label has no scientific value.

In these discussions I'm always reminded of a childhood story of Richard Feynmans (you can find it on youtube).He tells the story of his father taking him to the woods to observe birds. But they never learned all the names of the birds, because his father would remark: "If you just know all the names of all the birds in the world that still means you know nothing about birds".

Likewise people get hung up over whether it's eta or psi or gamma or whatever in mathematical formulae. It's just labels. Labels are interchangeable and convey no information. If you think calling/not calling Pluto a planet is somehow important then you don't know the first thing about science.

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